Nanoimprinting is a pattern forming technique that presses a mold (commonly referred to as a mold, a stamper, or a template), on which a pattern of protrusions and recesses is formed, against resist coated on a substrate, which is an object to be processed. Pressing of the original onto the resist causes the resist to mechanically deform or to flow, to precisely transfer a fine pattern. If a mold is produced once, nano level fine structures can be repeatedly molded in a simple manner. Therefore, the nanoimprinting method is an economical transfer technique that produces very little harmful waste and discharge. Therefore, there are high expectations with regard to application of the nanoimprinting method in various fields.
Technical developments are actively being pursued in the application of nanoimprinting to the fields of semiconductor and hard disk production, due to the advantages described above. Formation of super fine patterns on a ten and several nm scale is required in the production of next generation semiconductors and hard disks. There are reports that a high resolution of a 15 nm scale will be necessary by 2015, in ITRS (International Technology Roadmap for Semiconductors) 2011, for example.
Accordingly, in the production of a mold having such a super fine pattern, main chain breaking resists having a copolymer of an α-chloroacrylate ester compound and an α-methylstyrene compound as a main component (ZEP520A by Nippon Zeon Co., Ltd., for example) are widely utilized as a non chemically amplified resist that facilitates obtainment of high resolution. In a main chain breaking resist, the main chain of a polymer is broken by exposure to radiation such as an electron beam, and the molecular weight decreases only at portions that have been exposed. Accordingly, patterns are formed by a difference in dissolution rates of the exposed portions and unexposed portions with respect to with respect to a solvent, in the case that such a resist is utilized.
For example, n amyl acetate, which is a carboxylic acid ester solvent having an alkyl group (e.g., ZED-N50 of Nippon Zeon Co., Ltd.) is widely used as a developing fluid for a resist such as that described above. Further, propylene glycol monomethyl ether acetate (PGMEA), which is a carboxylic acid ester solvent having an alkoxy group (Japanese Patent No. 3779882), and a solvent having the chemical structure of at least two of the phenyl group acid group, a ketone group, and ether group (Japanese Unexamined Patent Publication No. 2006-227174) are also known as developing fluids.
Meanwhile, cold temperature development is known as a developing method having high resolution (Japanese Unexamined Patent Publication No. 2011-215242, L. E. Ocola and A. Stein, “Effect of cold development on improvement in electron-beam nanopatterning resolution and line roughness”, Journal of Vacuum Science & Technology B, Vol. 24, No. 6, pp. 3061-3065, 2006 and H. Wang et al., “Low temperature ZEP-520A development process for enhanced critical dimension realization in reactive ion etch etched polysilicon”, Journal of Vacuum Science & Technology B, Vol. 25, No. 1, pp. 102-105, 2007). Cold temperature development executes development while maintaining developing fluid in a cold temperature state within a range from 0° C. to approximately 5° C.